Kitchen Garden Forum

I don't know the exact age of this machine but as label says Birmid Qualcast (H&GE) Ltd I assume it is 1980s. Part No is L23981, Serial No. 039643/I. Electronic ignition and delOrto carburettor. Engine No. G 581132. Can anyone confirm age?
However my real problem is that after a few minutes the engine starts to make a loud 'clacking' sound and loses power and halts.
10 years later and I have now stripped the engine - decoked (it wasn't that bad), replaced head and other gaskets on carb. Also had the carb ultra sonically cleaned. I didn't go as far as removing the valves on this strip down but movement and seating seemed ok. After a few pulls it started and ran well and pulled very well when mowing a strip. Was then going to optimise idle speed/jet position but then the same 'clacking' noise and loss of power and stops. Could restart it once but soon the same problem.
The gap between tappet/lifters and valve rods seemed to be ok.
Any suggestions?

The governor?

Thanks for a great suggestion. I will check. The noise sounds more metallic and my thinking was it is more valve related but I couldn't see a valve seating problem unless it only shows up when hot.
Do you have experience of the governor hitting something or making/initiating a loud clanging noise?
Many thanks for your reply.

I'm no mechanic but from memory there's a section of galvanised sheet metal affected by the speed/strength of the cooling air running under the shroud the pulls start is on.

That would "clack" rather than clank or grind as it hits or bounces off something in its way?

Thanks. My governor 'plate' is plastic rather than metal and there is no sign of damage to it or flywheel. If my use of the word clacking implies not metallic then I have used the wrong word. The noise definitely sounds metallic.
Many Thanks

Problem turned out to be a loose inlet valve seat.

Inlet valve seat successfully punched and peened in place as per B&S guide. Re-lapped valve and seats (on both valves).

Following rebuild motor starts first time every time and no recurrence of the noise during two ten minute runs.

A good sign is that setting idle mixture and speed was as straightforward as it should be....

Many thanks

Thanks for the feedback on the cause.